If you don’t you need Sentry Advanced Monitoring. Now you can see everything they do, everything they say, everything they download, everyone they talk to.
And they’ll know that you do not trust them, that you have no faith in them. And you are probably the one that would hate if it someone did this to you. But hey, they are just kids – and you know better. Of course you do.
(and don’t forget, you can spy on everyone else in the family too! Who does your spouse IM? What sites do they look at? Will they smile and say “Thanks for keeping safe!” when they find out? I think not.)